A Calcium-Nickel Phosphate

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A Calcium-Nickel PhosphateDehydrogenation CatalystE. C. BRITTON, A . J . DIETZLER, AND C. R. NODDINGSThe Dow Chemical Co., Organic Research Laboratory, Midland, Mi c h .

N E W and selective This research was undertaken to provide an effectiveA catalyst has been catalyst for the dehydrogenation of n-butenes to 1,3-developed for the dehydro- butadiene, using superheated steam as heating mediumgenation of n-butenes to and diluent . catalyst.1,3-butadiene(1) Ultimate A calcium-nickel phosphate catalyst, promoted withyields of 1,3-butadiene of 93 chromium oxide, has given excellent results. Ultimate 93 SCOPE OF THE CATALYSTto 97 % have been obtained to 97% yields of 1,3-butadiene have been obtained in lab-in laboratory units at n- oratory units at conversion levels of 20 to 45%. in plant Calcium-nickel phosphatebutene conversions of 20 to operations, ultimate yields of 1,3-butadiene of 86 to 88 % is effective for the dehydro-45y0, In plant operations have been obtained at 35% n-butene conversion. genation of olefins with fo urultimate 86 to 88% yields Industrial use of this catalyst should result in improved carbon atoms in the chain.of 1,3-butadiene have been yields of 1,3-butadiene from n-butenes. In commercial Thu s, n-butenes and methyl-obtained a t a 35% % -butene trials the new catalyst has significantly increased plant butenes are dehydrogenatedconversion level (6). Ethyl- capacity for this important synthetic rubber intermediate. in good yields with highbenzene has been selectively It is of particular interest where efficient utilization of n- selectivity to 1,3-butadiene

the carbon deposited duringthe process period and forsubsequent oxidation of th e

dehydrogenated to styrene bute neiis necessary.over this catalyst.catalyst did not change in 3l/* months of continuous op erationin the laboratory unit, and remained constant at all conversionlevels except when operated at temperatures where thermal crack-ing affected selectivity. Of particular importance is the high n-buten e utilization a t high conversions which are realized withthis catalyst.The catalyst of this discussion is a calciu m-nickel pho spha testabilized with chromium oxide. Th e comp osition of the calcium-nickel phosphate corresponds approximately to the formulaCad%(PO&.

Prior to this paper the production of 1,3-butadiene by the de-hydrog enation of n-bu tenes in th e presence of steam over 1707catalyst was described by Xearby (3). Ultim ate yields of 1,3 -butadiene of 70 to 85% were obtained at n-butene conversion lev-els of 40 to 20%. Th e ultimate yield was shown to varywith the conversion level. Grosse, Morrell, and M avity ( 2 ) av edescribed the dehydrogenation of n-butenes a t reduced pressuresover alumina-chromia catalysts. The once-through yields variedfrom 11to 30% and ultimate yields up to 79% resulted.The p reparation, phy sical properties, use, performance in lab-oratory units, and peculiarities of calcium-nickel phosphate de-hydrogenation catalyst are discussed.

The selectivity of th e

DEFINITlON OF TERMSBy conversion is meant t he moles of n-butenes disappearing per

pass through the catalyst per 100 moles n-butenes passed throughthe catalyst.Selectivity or ultimate yield is the term given to the moles of1,3-butadiene produced per 100moles of n-butene disappearing.Space velocity is the volumes of gas passed through the cata-lyst bed per volum e of cataly st per h our, c orrected to 0' C. and760 mm. of m ercury pre ssure, assuming a perfect gas.Th e steam ratio is the molar ratio of steam to n-butenes passedover the catalyst.The process period is that portion of a cycle during which n-butenes and steam are passed through the catalyst and 1,3-buta-diene is produc ed.Th e regeneration period is that portion of a cycle during whichair and steam are passed through the catalyst for the removal of

and isoprene, respectively.Olefins with a carbon chaingreater than four are notselectively dehydrogenated to diolefins.Propane, propylene, butane, isabutane, and isobutylene pas3over the catalyst in th e presence of steam with essentially no con-version.Ethylbenzene is dehydrogenated selectively to styrene, and iso-propylbenzene t o a-methylstyrene.CATALYST PREPARATION

Th e following is a typical preparation of calcium-nickel phos-phate:Nine and one-half kilograms of a dilute aqueous ammoniasolution, containing 372 grams (21.9 moles, 1.56 moles excess) ofammonia, were added w ith stirring t o 90.7 kg. of a dilute aqueoussolution of o-phospho ric acid. This solution contained 665grams (6.78 moles) of phosphoric acid. To the resultant am-monium phos hate solution was added in 2 hours with stirring a t25" to 30' C 37.6 kg. of an aqueous solution containing 986grams (8.88 moles) of calcium chloride and 245 grams (1.02moles) of nickel chloride, NiC12.6HtO. Dur in this treat me nt aflocculent precipitate of calcium-nickel pfosphate formed.After addin the ingredients, stirring was continued for 0.5 hour,The pH of t k s slurry was 8.0. The mixture was allowed to standfor 6 hours during which time the calcium-nickel phosphateset tled to about 40% of the original volume. The supernatantliquor was removed by decantation and the residue washed bydecantation until the final washings were substantially free ofchlorides and soluble nickel salts. Th e slurry of calcium-nick elhosphate was then filtered. The filter cake was dried fo r 12{ours a t 60" C. and finally for 24 hours at 130' C . Th e productwas a hard yellow gel.Th e following is a typical chemical analysis of this product:

MaterialPO4CaNiHl 0

Weight '%55 .7731.315 .226 .24 -The calcium to nickel atomic ratio was 8.79 to 1. The calciumplus nickel to phosp hate ratio w as 1.47 to 1.The calcium-nickel phosphate gel was ground to pass a 28-mesh screen, and then mixed w ith 2 % of the graphite and chro-mium sesquioxide stabilizer (when used) and compressed into 3/ ,$

X s/16 inch cy lindrical pellets.2871


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2872 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 43, No. 12Th e graphite was removed from th e catalyst pel lets by passinga mixture of steam a nd air over the cataly st a t 350' to 650' C.Th e pel lets then had an ap parent bulk densi ty of ab out 1.

NATURE OF THE CATALYSTThe calcium-nickel phosphate catalyst, after precipitation anddrying, was shown to be amorphous by x-ray and electron dif-fraction studies. After roasting or use it was foun d to be a single-phase solid solution containing p-calcium phosphate in which

Borne of the calcium ions had been replaced with nickel ions,Figure 1 hows a comp arison of t he x-ray diffraction pattern s of p-calcium phosp hate an d p-calcium-nickel phosphate. The p-cal-cium phosphate phase is shown in pattern 8 , nd th e p-calcium-nickel phosphate phase in pattern B .

A

B

Figure 1 . Comparison of S - N a y 1)iifraction Patternso f p-Calcium Phuspha Le a ~ i d -Calc~ium-Sicl.c.IPhospha I e

. I. ?-Cnlrium plroiglioteI # . j-(:ulcium-nirhel pho.pliatr

These pat terns were made by the equatorial shutter methodwith both patterns on the same film, using filtered CuK, radia-tion.Since the ionic radius of nickel (0.78 A , ) s less than that of cal-cium (1.06 A ), he lattice of the calcium-nickel phosphate is con-tracte d. This is shown by the lower value of the interplanarspacings represented by th e lines on th e pattern .

Th e camera radius n-as 71.8 mm.

Th e ionic stru cture of th e calcium-nickel p hosphate cataly stwas further proved by magnetic susceptibility measurements.These studies showed that the nickel is present in the catalyst asnickel ions and th at these are dispersed throughout the mass. Inall samples of ca talyst examined, both unused and used, th eeffective magnetic moment of the nickel m-orked out to be 3.5Bohr magnetrons (6). This is practically within the range 2.9 to3.4 generally reported for the m agnetically dilute nickel ion.Calcium-nickel pho spha te after roasting has a low surface areaas determined by nitrogen adsorption. Th e surface areas of bo thfreshly prepared and used catalysts vary be tveen 2.71 and 7.33square meters per gram (4).Th e bulk density of the pelleted cata lyst is abo ut 1gram per ml.The absolute density of the unused calcium-nickel phosphate is2.475 to 2.500.

LABORATORY APPARATUSFURNACERRANGEM ENT.he ca talyst tube, which was a 1 nc hiron pipe size X 46 inch Type 446 stainless steel tu be, was placedin a vertical position inside a 37/16 X 40 inch aluminum bronze

block enclosed by electrical heating elements. Th is uni t wasplaced vertically in a 103/ s X 45.5 inch transite flue pipe. T h espace between the heating elements and th e transite case wasfilled with Filter-Cel.A close tem pe ratu re control of +2O C. over the central 90% ofth e aluminum bronze block xa s realized by using three independ-ent ly controlled heating coils-two 6-inch coils a t the ends of theblock and a 28-inch coil a t the cen ter of th e block.One-quarter inch porcelainBe d saddles were placed in th e bottom of the catalyst tube extend-ing to a point 4 inches above the bottom of the aluminum bronzeblock. Th en 150 ml. of catalyst were placed in th e reaction tube.Th e d e p t h of the catalyst bed u-as 11 inches for a 150 ml. cataly stcharge. T he upper 25 inches of th e cataly st tube were filled with

CATALYSTUBE RRAKGEM EKT.

0.25-inch B erl saddles and served as the preheating section.gas flow was dow nward. T h e

CATALYST USE FOR 1,3-BUTADIEKE PRODUCTIONACTIVATION.T h e chromium-oxide stabilized calcium-nickelphosph ate catalyst as formed contains graphite. This graphitemus t' be remove d before the c atalys t can be used effectively.Th e catalyst is f i rst heated to 200" to 300" C. in the presenceof carbon dioxide or nitrogen. Stea m is no t to be used duringth e initial warmu p or th e pellet stren gth will be decreased. Th etemp eratu re of t he ca talyst is then raised in th e presence ofs team to 600' C. a t the ra te of 25 ' to 50" C. per hour with 5niininium steam space velocity of 800.

t o 600" C., the catalyst changes from an amorphous to a crystal-line state . If steam is not used during this transition th e catalystpellets will shatte r. When the cata lyst temp eratu re reaches600" C., air along w ith t,h estea m is passed over th e catalyst at aspace velocit'y of about 5. Thc air space velocity is kept between5 and 25 until th e initial rapid bu rning of th e graphite has sub-sided, and the air space velocity is adjusted so t ,hat the catalystbed temperature does not exceed 650" C. Kh en the init ial rapidburning has ceased (in about 1 hour in the laboratory unit) , theair space velocity should be increased to 100 t o 150 and keptthere until all of the graphite is burned out . This may requireabout 6 hours and m ust be checked by the carbon dioxide contentof th e effluent gas. In a plant unit the initial combustion frontpassed through the catalyst bed in about 14 hours and thegraphite Tvas all removed in about 30 hours.This c atalys t is operated c~-clically, .5 to 1 h o u ron a process using n-butenes and steam, and 0.5 t o 1 hour onregeneration using air and steam. For successful operation aninitial break-in tim e of ab ou t 10 days is required before all ope rat-ing conditions can be stabilized.PROCESSERIOD. he following conditions of operation arerecommended for the 10-day break-in stage:A &earn ratio of a t least 21.A n-butene space velocity (neglecting the presence of s team)such tha t the n-butene linear velocity at conditions of op eratin gtemp eratu re and pressure, assuming a perfect' gas, is greater than0.2 feet per second thro ugh a n em pty space equivalent in size andshap e of th e bed. Space velocities betwee n 85 and 400 have beenused but a n-butene space velocity of 90 to 150 is recommendedwith th e length of the process period being 0.5 to 1 hour.The catalyst temperature is s tar ted low, about 525" C., an draised 10" C. per cycle until a conversion level of no t over 30% i sreached.The following conditions of operation are used after the break-instage:A minimum steam rat io of 18 is used.Any n-butene space veloci ty in the 85 to 400 range may beused but this should be held constant from cycle to cycle. Forefficient cataly st use, a low space velocity throug h a deep catalyst.bed-e.g., 90 to 150 space velocity in a 6-foot deep bed-is desir-able with th e length of t he process period being th e same as fo rthe regeneration period.The catalyst temperature depends on the n-butene space veloc-ity used and th e conversion level desired, and m ust be increasedto ma intain c ons tant conversion as the ca talyst ages.The conversion should be held at 30 to 40% in a 6-foot deepcataly st bed with a n-butene space velocity of abo ut 100.REGENERATIOXERIOD.T he length of this period is equal t oth at of the process period.Th e temperature of th e air-steam mixture should be the sam eas tha t of the n-butene-steam mixture fed during th e processperiod. Th e maximum catalyst temperature during regenera-

tion should be kept below 675" C. Th e steam and air flow ratesmay be varied to keep below this temperature. A minimumste am space velocity of 600 is required; an air space velocity ofabou t 150 is suitable. Good mixing and distribution of th esteam and air are essential.Com plete carbon removal is required w-it 'hin th e first threequa rters of the regeneration period. Th e last quar ter of thisperiod is an oxidation period wherein no ca rbon is being burned.

While heating from 300

OPERATION.

EFFECT OF ADDING CHROM1UR.I OXIDE TO CALCIUM-NICKELPHOSPHATECalcium-nickel phosphate alone is an active a nd selective cata-lyst for th e dehydrogenation of n-butene8 to 1,3-butadiene. T headdition of chromium oxide to calcium-nickel phosphate has theeffects of stabilizing the c ata lys t, of increasing th e cata lyti c activ-


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December 1951 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y

TABLE . COMPARISOKF ACTIVITYOF CALCIUM-NICKELPHOSPHATEITH CALCIUM-NICKELHOSPHATETABILIZEDITHCHROMIUMXIDE

12318192021224249256

39.038.63 8 .43 2 .832.43 2 .032 .O2 9 . 4

4 2 . 44 3 . 04 3 .44 4 . 44 4 . 243.04 3 . 44 2 . 84 2 . 2

ity over tha t of th e calcium-nickel phos phate component alone,an d of prolo nging th e effective life of th e cataly st.I n T ab l e I is shown a comparison between the calcium-nickelphosphate alone and the same calcium-nickel phosphate contain-ing 1% of chrom ium oxide .The experiments described in Table I were run under the fol-lowing conditions: n-buten e space velocity, 300; steam ratio,20; cycle time, 1 hour; and temperature, 650" C. The condi-tions of the experiment, especially with respect to temperature,are severe for a new catalyst bu t show very definitely th e stabili5-ing effect of added chromium oxide.

CATALYST LIFE STUDYTable I1gives the average results of two laboratory life studieson calcium-nickel phosp hate chromium-o+de catalysts. Lifes t udy A was mad e on one of th e first pla nt lots of c ataly st whilelife study B was made on more recent pla nt production.

TABLE1. LIFE STUDY AT AO N CALCIUM-NICKELHOSPHATECHROMIUM-OXIDEATALYSTSLife Study Cyole Temperature,No. KO. c . Converaion Selectivity

A 0-2400 600-630 26.4 92.9B 0-2037 590-630 30.0 93.7

Both tests were run under substantially identical conditions.n-Butene space velocity was from 188t o 197. The steam ratiowas 21.4. Th e cycle time was 1 hour-i.e., 28 minutes on proc-ess, a 2-minu te purge, 28 minutes regeneration, and a 2-minutepurge. Regeneration air space velocity was 85 an d 150 ml. ofcatalyst in an 11-inch deep bed was used. Tem perature on lifes t udy A was adjusted to maintain abo ut a 25% conversion, whilethe temp erature on l ife study B was adjusted to maintain a 30%conversion.The catalyst used in life study B was of higher activity thanwas that used in l ife study A. A temperature rise of 30" C.,from 600" to 630" C. , was required to maintain about a 26% con-

version for 2400 cycles in life study A; a temperature rise of40' C., from 590' to 630' C., was required to maintain a conver-sion of 30% for 2000 cycles in life stu dy B.

TABLE11. PRODUCT AND FEED ANALYSISMaterial -Mole o/o in Feed Mole % in Product

Carbon dioxidqCarbon monoxideHydrogenMethaneEthane and ethylenePropane and propylene1 3-Butadiene 1 . 1n-Butenes 7 0 .5Butanes 2 2 . 3Pentane and pentenes 0 . 8Ikobut ylene 4 . 9

0 . 70 . 31 7 .60 . 80 . 50 . 21 6 .52 94 1 .31 8 .20 9

Th e selectivities remained unchan ged during these life studies.This fact has been confirmed in plant usage ( 5 ) .The actual life of the catalyst is at present unknown. A plantru n of 6l/~ onths has been completed. D ata on this will bepublished (6).The conversions and selectivities were calculated by a carbonbalance method from an analysis of th e total effluent gas aftercondensation of the steam, and corrected for the carbon depositedon the catalyst. This correction is equivalent to about 0.05moles of n-butene per 100 moles of hy drocarb on feed at a conver-sion level of 2 9% with a cycle leng th of 1hour. A correction of0.4 was found when th e catalyst was operated a t a conversionlevel of 40% using 2-hour cycles ( 5 ) . The catalyst bed in thiscase was 1 nch in diameter and 30 inches deep. The n-butenespace velocity wab 100. Table I11 shows the com position of atypical product gas and the analysis of the n-butene feed.EFFECT OF VARIATION OF STEAM TO n-BUTENE RATIO

In order to obtain high selectivities with calcium-nickel phos-phate catalyst i t is essential tha t the dehydrogenation be run inthe presence of steam. In Table IV is shown th e effect of v aria-tion of th e molar steam to n-butene ratio on th e conversion andselectivity of n-buten es to 1,3 -butadiene over a stabilized calcium-nickel phosp hate catalyst.

TABLEV. EFFECT F VARIATIONF STEAM ATIO NCONVERSIONN D SELECTIV~TYMolar Ratio,Steam toRun No. n-Butene Conversion Selectivity

ABC21.41 5 .12 1 . 4

3 0 . 53 3 .02 5 .09 2 .07 8 . 054 O

Other cond itions of operation for th e above experim ent ar e aafollows: tem erature , 630" C.; n-butene space velocity, 193;cycle time, 1 f our ; catalyst age a t the star t of Run No . A, 1400hours on stream; Run No. A, average of 323 cycles; Run No . B,average of 328 cycles imme diately following Ru n No . A; R u nNo . C , average of 341 cycles immediately following Ru n No. B ;Run Nos. A, B, an d C were parts of one continuous experiment,When the steam ratio was decreased to 15.1 in the laboratoryunit the conversion increased to 33% and the selectivity droppeda t once to 78%. On returning to the 21.4 steam ratio the selec-tivity returned to the original value, but the eonversion waslowered t o 25% and remained a t this level until completion of th eexperiment.

Other experiments have shown that a steam ratio of 18 to 19may be used successfully after th e first week of o peration .Increasing steam ratios abov e 21.4 in the laboratory isothermalunit caused a gradual decrease in conversion with no change in se-lectivity.EFFECT OF n-BUTENE SPACE VELOCITY ON CONVERSION ANDSELECTIVITY TO 1,5-BUTADIENE

Decreasing the n-butene space velocity at a given tempe ratureThis effect is illustrated inevel results in increased conversion.

TABLE. E F F E CT F n-BUTENE SPACE lTEL0CITY O NCONVERSIONND SELECTIVITYn-BbteneTemperature, Space Catalyst Age,c. Velocity Conversion Selectivity Cycles

600 100 31 .0 95 0 200600 193 2 5 .4 9 2 .0 200620 100 3 7 .6 5 7 .0 700620 193 27 .0 93.0 700630 100 38 .0 96.6 1200630 193 3 0 . 2 9 2 . 0 1400


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2814 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 43 , No. 12Table F'. As stated previously it is recommended that calcium-nickel phosphate catalyst be operated a t a low n-butene spacevelocity and in a deep catalyst bed because these conditions per-mit operation a t high conversion levels a t relatively low tempera-tures. In this way, therm al cracking effects are minimized andhigh production with e fficient n-butene utilization is realized.Th e large surges of cracked products a t the beginning of theprocess period, which have made 6-foot bed operation difficultwith other n-butene dehydrogenation catalysts, are not in evi-dence with calcium-nickel phosphate catalyst ( 5 ) .The da ta in Table V were obtained at a stea m ratio of 21.4 onthe same lot of plan t catalyst in laboratory equipment a s de-ecribed above.

EFFECT OF LENGTH OF CYCLE ON CONVERSIONIncreasing cycle time from 1 to 2 hours causes a decrease in11-butene con version of from 2 to 3 % as shown in Table V I ,

TABLE VI .Cyole Length,

E F F E C T F CYCLE TIME N COKVERSIOXHours Conversion Selectivity

1 4 1 . 2 9 7 . 42 38 .8 97 .3

Table V I shows that no change in selectivity was apparent.throu gh a 2-hour cycie gave the following results:At a 25% conversion level samples taken at various times

Sampling Time,Minutes afterStar t of Cycle2173247

Conversion2 8 . 42 5 . 72 4 . 82 3 . 1

A 25.1% conversion was obtained for the total 60-minuteprocess period of t he 2-hour cycle.EFFECT OF MATERIAL O F CONSTRUCTION ON SELECTIVITY

Nickel containing stainless steels in contact with th e catalyst inthe catalyst case will cause erratic action of th e catalyst w ith a de-crease in catalyst selectivity. Thi s effect is shown in Table VII.The experiment described in Table VI1 was run at a n-butenespace velocity of 170, a stea m ratio of 21.4, and w ith a cyclelength of 1 hour.The decline in selectivity was quite rapid from 92% at thes ta r t of the run to about 70 % a t the end of 2399 cycles. In aTy pe 446 stainless steel tube as shown in life test A , Table 11, thissame catalyst showed no loss of sele ctiv ity in 2400 hours of op era-t ion.Life tests in T ype 446 stainlees steel, fused silica tubes, WalshX X brick, and in bricked c atalyst cases covered with a finish coatof Smoothset have shown no adverse effect of these materials oncatalyst activity.

CATALYST POISONSNickel-containing steels in contact with the catalyst or anycontamination of th e catalyst with nickel compounds will resultin lowered selectivity.Colita mina tion of th e cataly st with a num ber of metallic oxides,especially the oxides of the alkali and alkaline e arth m etals,Causes lowered selectivity. Iron oxide coatings on the pellets,such as have been encountered in the laboratory units where thiswork was done and in com mercial units, have no t affected catalystactivity.Carbon deposits on the ca talyst cause lowered conversion, andif allowed to accumulate on the catalyst throu gh successive cyclesn,ill cause lorn-ered selectivities.

TABLE II . EFFECTF KA2 REACTION UBE N SELECTIVITYO F CALCIUM-NICKELHOSPH.4TE CHROYIUY-OXIDE CATALYSTFO R DEHYDROGENATIONF n-BUTESES TO I,%BUTADIENE

Temperature,Cycle No. O c. Conversion Seleotivity1233816038171146127115881902197222282399

610610620620620620620620630630630

3 0 . 92 5 . 23 0 . 32 7 . 13 0 . 53 0 . 62 8 . 22 5 . 626.73 1 . 62 9 . 4

8 2 . 39 0 . 18 8 . 38 6 . 48 0 . 97 6 . 87 9 . 87 9 . 58 3 . 07 2 . 37 0 . 7

EFFECT OF IMPURITIES IN FEEDThe following impurities in th e feed under th e conditions of th etest h ave not effected catalyst, activity:Acetone to 0.5% of the hydrocarbon feed; organic chlorides asmethyl chloride to 15 p.p.m .; ammonia to 100 p.p.m.; carbondioxide in the quantities found in the steam and formed by thereaction; and butanes and isobutylene.OTHER LMATERIALS CATALYTICALLY DEHYDROGEVATEDEthylbenzene was selectively dehydrogenated t o styrene overcalcium-nickel phosphate catalyst as shown in Table VIII.

TA B LE YI I I . DEHYDROGENATIOS O F ETHYLBEXZEXE TO S T Y R E N EOVER CALCIUM-NICKELHOSPHATE C.4TALYST

Ethylbenzene - Tempera-Space Steam ture,Velocity Ratio c. Conversion Selectivity

The experiments described in Table VI11 were made by run-ning 1 hour on process and 0.5 hour on regeneration. The effectsof temp erature, e thylbenzene space velocity, and steam ratio areshown.Isopropylbensene, when passed over the catalyst at a space ve-locity of 54.5 and a steam ratio of 18.4 a t 575' C., showed a con-version of 34.8% with a selectivity of 88 .9% to a-methylstyrene.ACKNOWLEDGMENT

This paper is based principally on w ork done by the Organic Re -search Laboratory, the Chemical Engineering Laboratory, theSpectroscopy Laboratory, and the Main Laboratory of the D o wChemical Co. Th e assistance of various members of t h e e groupsis greatly appreciated.We are indebted to Polynier Corp., Ltd., Sarnia, Ontario, forits cooperation in further laboratory studies and developmentof the p lant use of this catalyst.

LITERATURE CITED(1) Britton, E. C., and Dietaler, -4. . , U. S. atents 2,442,319 an d2,442,320 (May 25, 1948), 2,456,367 and 2,456,368 (Dec. 14,1948); Heath, S. B . , U. . Patent 2,542,813 (Feb. 20, 1951).( 2 ) Grosse, A . V., Morrell, J. C., and RIavity, J. M., IND. NG .CHEM., 2, 309-11 (1940).(3 ) Kearby, K . K., I b id . , 42, 295-300 (1950).(4) Kummer, J. T. , Mellon Institute, private communication.( 5 ) Polymer Corp., Ltd., Sarnia, Ontario, Can., private oommunica-(6 ) Selwood, P. W ., Northwestern Cniversity, private communica-RECEIVED ay 4, 1951.

tion.tion.

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A Calcium-Nickel Phosphate